In the field of radio access network, equipment manufacturers will usually develop a variety of access devices with multiple modes on one hardware platform, such as base stations with modes of wideband CDMA (WCDMA), Time Division-Synchronous CDMA (TD-SCDMA), Code Division Multiple Access (CDMA), LTE Time Division Duplexing (LTE-TDD), LTE Frequency Division Duplexing (LTE-FDD) and the like. In order to save costs, clock board is often designed to be combined with main control board and transmission board as one piece. More and more emergence of multi-mode integration scenarios, for example, an evolved integration of the TD-SCDMA and the LTE-TDD, and a mode integration of the LTE-TDD and the LTE-FDD, may induce integration in an isolated condition of maintenance and service of the hardware platform, that is, the device may appear in two radio operation-maintenance networks at the same time.
The particularity of the clock synchronization signal has determined that only one clock source is provided in one machine frame at any time. That is, multiple base station systems (two base station systems in general) in the same machine frame can use only one clock. In prior art, usually, following two schemes could be selected to solve the problem about the clock source of two base station systems in the same machine frame. In the first scheme, as shown in FIG. 1, layout of the boards of the platform is redesigned such that the clock board is separated to form a mode of clock board+main control board+base band board; in the second scheme, as shown in FIG. 2, a main control board in a certain base station is used as a clock output board, so that dual-mode base station system could be coupled with the platform independence sacrificed.
For above first scheme in prior art, it is necessary to redefine the function distribution of the boards of the platform and develop new boards, so that there is a great impact on existing commercial equipments, and original platform evolution ideas would be changed, resulting in high costs. For above second scheme in prior art, the main control board capable of outputting clock does not used to output clock, which is a waste of capability of the device, and with over coupling. Mode A could not operate independently of Mode B; especially when the Mode B is upgraded, Mode A may be caused out of service, which would be not acceptable from the point of operators.
As it could be seen, although above two existing schemes may solve the problem of clock synchronization of multiple base station system in the same machine frame to some extent, they have problems such as high costs, loss or waste of function and the like, such that the clock synchronization of multi-mode base station system in the same machine frame could not be achieved in a simple, effective, low-cost manner.